The US vice-president is demanding Hamas agree to an immediate six-week ceasefire and urging Israel to do more to boost aid deliveries to Gaza, where she says innocent people are suffering a "humanitarian catastrophe".
In some of the strongest comments by a senior US government leader to date, Kamala Harris pressed the Israeli government and outlined specific ways on how more aid could flow into the densely populated enclave where hundreds of thousands of people are facing famine, following five months of Israel's military campaign.
"Given the immense scale of suffering in Gaza, there must be an immediate ceasefire," Ms Harris said.
"There is a deal on the table and, as we have said, Hamas needs to agree to that deal. Let's get a ceasefire.
"People in Gaza are starving. The conditions are inhumane and our common humanity compels us to act … The Israeli government must do more to significantly increase the flow of aid. No excuses."
On Sunday, a Hamas delegation arrived in Cairo for the latest round of ceasefire talks, billed by many as the final hurdle for a truce, but it was unclear if any progress was made.
Israeli news agency Yedioth Ahronoth reported that Israel boycotted the talks after Hamas rejected its demand for a complete list of hostages who were still alive.
Washington has insisted the ceasefire deal is close and has been pushing to put in place a truce by the start of Ramadan, a week away. A US official said on Saturday Israel had agreed on a framework deal.
An agreement would bring the first extended truce of the war, which has raged for five months so far with just a week-long pause in November.
Under a new truce, dozens of hostages held by Hamas militants would be freed in return for hundreds of Palestinian detainees.
One source briefed on the talks said on Saturday that Israel could stay away from Cairo unless Hamas first presented its full list of hostages who were still alive. A Palestinian source told Reuters that Hamas had so far rejected that demand.
After the Hamas delegation arrived, a Palestinian official told Reuters the deal was "not yet there". There was no official comment from Israel.
In past negotiations, Hamas has sought to avoid discussing the wellbeing of individual hostages until after terms for their release are set.
The death last week of more than 100 Palestinians approaching an aid truck in Gaza has highlighted the severe humanitarian crisis in the densely populated enclave, an incident Ms Harris recalled during her speech.
"We saw hungry, desperate people approach aid trucks, simply trying to secure food for their family after weeks of barely any aid reaching northern Gaza, and they were met with gunfire and chaos," Ms Harris said.
